The present invention relates to silica feedstock compositions. More particularly, the present invention relates to silica forming feedstocks, and the manufacturing of optical waveguide preforms.
Various processes are known that involves the production of metal oxides from a variety of feedstocks. Such processes require a feedstock and a means of catalyzing oxidation and combustion of the feedstock to convert the feedstock into finely divided aggregates called soot. This soot can be collected on deposition surfaces, ranging from a collection chamber to a rotating mandrel. The soot may be simultaneously or subsequently heat treated to form a high purity glass article. This process is usually carried out using specialized conversion site equipment having an arrangement of delivery tubes and flame generating burners.
Much of the initial research that led to the development of such processes, including flame hydrolysis, focused on the production of silica glass products such as bulk fused silica. Selection of an appropriate feedstock which can be converted into the desired silica glass composition is an important aspect of such research. Commercial production of silica glass by such a conversion process became and is continued to be dominated by the use of silicon tetrachloride (SiCl4) as the feedstock""s source of silicon. The high vapor pressure of silicon tetrachloride and its purity has made it a useful and convenient source of vapor for conversion into SiO2 soot. This use of silicon tetrachloride provides a high purity silica glass and has been the commercially preferred method of manufacturing silica glass for use in optical waveguide products and particularly the manufacturing of optical waveguide fibers and their preforms. Such use of silicon tetrachloride in the manufacturing of optical waveguides has led to the adoption of other similar chloride-based feedstocks which are compatible and used in conjunction with silicon tetrachloride to provide beneficial silica glass compositions and corresponding indexes of refraction which are able to guide light. The silica glass dopant feedstock vapor GeCl4 is used in conjunction with SiCl4 vapors to form silica glass compositions doped with appropriate levels of germanium dioxide which are utilized in the manufacturing of optical waveguides. This has led to the presently accepted use of SiCl4 vapors and GeCl4 vapors in the manufacturing of optical waveguide silica glass cores doped with GeO2, even though such feedstocks result in the production of hazardous by products such as hydrochloric acid (HCl).
In light of this, there is a need for a germanium doped silica feedstock and a method of forming optical waveguide preforms which results in an optical waveguide product such as an optical fiber while avoiding the hazardous by products of the prior art.
Accordingly, the present invention is directed to a silica forming feedstock and method of forming optical waveguides and optical waveguide preforms that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
The principal advantage of the present invention is to provide a silica forming feedstock, which produces a germanium, doped silica glass which allows for the manufacturing of optical waveguides and preforms thereof without the production of hazardous halides.
Additional features and advantages of the invention will be set forth in the description, which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the methods and compositions of the invention particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages in accordance with the purpose of the invention, as embodied and broadly described, the invention is a fluid feedstock including siloxane and a germanium compound.
In another aspect, the invention includes a method of using the inventive feedstock in the formation of optical waveguide preforms and optical waveguides.
In a further aspect, the invention includes the making of optical waveguide preforms, which are predecessors and physical embodiments of an optical waveguide product prior to the final forming of the preform into the optical waveguide product, such as by drawing a preform into an optical waveguide fiber.
In another aspect, the invention includes the forming of optical waveguide preforms by such processes as cladding, drying, consolidating, stretching, caning, overcladding, and reconsolidating.
In a further aspect, the invention includes a method of making low loss optical fiber by converting a siloxane and germanium alkoxide feedstock into a GeO2 doped silica glass.
In another aspect, the invention includes an optical waveguide silica feedstock and an optical fiber silica feedstock, which includes a siloxane and a germanium alkoxide.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.